Reinforced glass matrix materials, i.e., glass matrix composites, are finding increasing use in the "intermediate" temperature range where composites enjoy advantages over alternatives, such as steel alloys and the like. In particular, aircraft operating at about mach 1, including both sub and supersonic speeds, frequently encounter temperatures in the *00-1500.degree. F. range, exposing many structural items to potential heat damage. At temperatures substantially above this range, solid ceramic materials are used. Below this range, reinforced resin materials, typically organic resins such as epoxy thermoset and various thermoplastic resins are employed.
Prior art attempts to form composites for the intermediate temperature, employing a glass matrix reinforced by ceramic fiber systems, comprise the formation of a slurry containing glass frit, destined to become the matrix, a resinous binder material and a solvent for the binder. A ceramic fiber tow or tow system is impregnated with the slurry, the glass being held in place by the binder. This type of formation system is difficult to handle, and reduces the control of the final shape and composition of the matrix. In particular, a very significant amount of the binder is needed to hold the powder in place, yet the binder must be removed . prior to consolidation of the glass matrix, which presents a slow process, and a costly problem. If the binder is not removed, voids in the matrix can frequently occur, substantially weakening the composite. Alternatively, if the binder concentration is reduced, the glass powder may be lost during handling, again, defeating the object, which is to obtain a uniform matrix of glass material, with ceramic reinforcement distributed homogeneously therethrough.
The above prior art process presents other problems as well. In particular, it is quite difficult to achieve substantial variations in the matrix/ceramic ratio, and thus, difficult to adapt the ceramic reinforcement loading value to meet various applications. Additionally, uniformity, or homogeneity of the distribution of the reinforcement fiber is difficult to achieve according to these prior art systems. Problems encountered in impregnation and binder handling essentially prevent a thorough intermingling of the matrix and fiber materials. Additionally, it is quite difficult to provide parts of complex shape and structure, without complicated multi-part tools, etc., the precursors are neither easily transported, nor easily worked with.
Accordingly, it remains an object of the art to provide a method by which a uniform, high density glass matrix material, reinforced with non-continuous ceramic fibers. Such as process should result in a composite, or precursor, which is susceptible of easy transportation, shaping and the like.